Hi overlander63--I have been recently researching 7.00x15 vs ST225/75R15 in the Goodyear family and came up with the following prices at WalMart for D load range: $107.20 vs $90.28, which now makes the 7.00x15 more expensive. This was not the case in the past. All of the other factors you list above are identical to what I have found. I have stayed with the original size 7.00x15 and never had a problem or flat with them, however availability on the road, is beginning to concern me so I may switch to ST225/75R15 next tire replacement.--Frank S

I would trust a Load Range D radial over any bias ply tire; this is a pretty heafty tire. Bias plys simply don't have the road holding quality of a radial. This could be be particularly important in a wet hard stop situation.

Well I blew out two front Marathons ST227/75R/15 on my recent May/June trip in hot weather. Admittedly, I was going too fast 70-75 mph. There are no warranties on these tires. I had moderate damage to the A/S lower panels. A replacement tire locally was $120 - but installed and balance and discarding the old tire --total $160. Because I'm taking off again in 2 weeks I bought 2 Marathons from TireRack.com for about $164.00 which included shipping to Texas. We need better tires I think.

SafeHarbor
The 7.00-15XC stands for the Michelin XCA. It was a radial but looked like (had the profile of a Bias Ply tire).
Is is no longer made in our size (15 or 16 inch rim).
The sidewalls are not the problem. The belts shift causing an air leak. The heat generated by running flat causes catastrophic failure. You cannot look at a radial and determine whether it has 60 PSI in it or 40 PSI. There just isn't that much difference in sidewall bulge.
Help us help ourselves.
Report these failures to the people responsible for investigating these problems.

These tire failures are not our fault folks. We have just been putting up with them for so long that we think it is a normal way of camping. It is not.
There are save, reliable and dependable alternatives to getting away from these failures other than going 45 mPH and changing tires every 3 to 4 years.
I have gone that route along with others.
I will await the hammering for this message.
Begginer

I'm not blaming the tires - I don't even know how old they are. One even has a slightly different sidewall from the other three.

My blowout was 7.5 miles into the trip going 45 mph, and I know how much air was in the tires. They all had 65 psi upon departing.

The separation, well, I wonder if I'm using the right word. The tread departed the tire in chunks, leaving the belts showing. Even after this, I had to drive another 5 miles (30 mph with the flashers going) to find a level place to change the tire. I checked that tire today. It STILL has 65 psi in it!

The trailer, except for some playing around in the pecan grove a couple of weeks ago, had been sitting since last October.

That was Saturday. On the previous Wednesday, I had all the tires off the trailer because I installed new backing plates. I critically looked at each tire for weather checking, bulges, irregular wear, etc. and I found no problems.

And how annoying - these were the tires that always had the Zip-Dee covers shading them.

I called Wal-mart. They can get the tires, but they won't change them on the RV. No problemo. I'll jack it on my ramps in their parking lot and carry them in one by one.

Next, question. I have the centramatics. Should I let them balance the wheel/tire anyway? (So far, I don't really see any reason not to.)

Then again, I might call around town and see if anybody's got the Snap-On balancer that Inland Andy recommends so I can get the hubs balanced with the wheels.

Found this info
because the design of most trailer suspensions dates back many decades, ST tires are designed for as soft a ride as possible so they don't transmit too much shock to the trailer and its contents. Trailer-tire sidewall stiffness is a compromise between P and LT designs. The desire for stiffer sidewalls is still occasionally cited as the reason for choosing a bias-belted trailer tire. While passenger-car tires are nearly all radials these days, ST tires are still available in bias-belted construction. Radial trailer tires are superior in all respects to bias-belted tires except in sidewall stiffness. Reduced tire heat, lower rolling resistance and softer ride are among the benefits of radials, not to mention extended wear. On the road, ST tires share some characteristics of passenger-car tires, but are closer to the design of light-truck tires. Trailer tires typically employ heavier steel or polyester cords and somewhat lighter sidewall construction than light-truck tires, and trailer tires typically run lower air pressures than their truck counterparts. This gives ST tires good load-carrying capacity, but with the desired softer ride, ST tires also have the advantage of rubber compounds that are specifically designed to resist deterioration from the elements, including sunlight and ozone, during extended storage.